On the otherhand, yeast-based toxicity assays revealed that the decolorizationof azo dyes under anaerobic conditions results in the formation ofreaction products that can have a higher cytoand genotoxicitypotential than the original dye and can be presumably attributedto colorless aromatic amines. The detoxification of the wastewatercontaining these products was only observed during the aerobicreaction phase of the AGS SBR system after 70 days of operation.